Final Drive upgrades

CMS-GT4

Active member
I wanted to start a topic on final drive upgrades. Final drives have been an inexpensive performance mod for many cars.

While it is not the easiest of mods to do to our cars, it might be a good solution for those who already plan on dropping their gearboxes for a clutch and it might be much more affordable in the long run vs having to get a huge turbo kit. Alltracs might get much more out of their ct26, ct20 or ct27 with a lower final drive. For those of us with taller than stock tires this helps bring our FD closer to stock.

Alltrac ratios
Final Drive: 4.285
1st (3.384); 2nd (1.913); 3rd (1.333); 4th (0.972) 5th (0.731)
Rev: (3.545)

RC Ratios
Final Drive: 3.933
1st (3.583); 2nd (2.045); 3rd (1.333); 4th (0.972) 5th (0.731)
Rev: (3.545)

Rally ratios
St185 Rally (1989.9/6):
Final Drive: 4.285
1st (3.230); 2nd (2.142); 3rd (1.518); 4th (1.258) 5th (0.731)
Rev: (3.545)

Here is a link to a calculator to see how the FD can effect your gears.
http://www.housemanautosport.com./ratio ... ulator.htm

Rav4 Gearbox
We have already discussed that a Rav4 gearbox is an option for a lower final drive and closer ratios. The only concern being the strength of the gearbox.
Links to threads:
http://www.alltrac.net/phpBB2/viewtopic ... light=rav4
http://www.alltrac.net/phpBB2/viewtopic ... light=rav4
http://www.alltrac.net/phpBB2/viewtopic ... light=rav4

Fensport 4.4 Final drive
I found this link that at one point the fensport y2k gt4 had a 4.4 fd.
http://www.motoraddicts.com/experts/blo ... elica99414
Spensport offers this final drive as an option in one of their gearset kits. I emailed them about getting the FD separate for the standard box.

Info from their page.
3.933 Final drive (25mph per 1000rpm, ie 200mph at 8000rpm), also available with 4.4 Final drive(22.5mph per 1000rpm, ie 180mph at 8000rpm).
http://www.fensport.co.uk/partsfiles/st205tuning.htm

However it seems like most cars that make too much power they can be better with a higher final drive.
http://www.modifiedcars.com/cars/Toyota/19345.htm

Anyhow, a lower final drive may be a good option for some of us with moderate power goals.

EDIT: Added final drive mod link for reference.
http://gtfour.supras.org.nz/428ratio.htm
 

CMS-GT4

Active member
So it looks like the MR2 guys had this idea as well. A 4.5 final drive was made for the mr2 by Phoenix Power. I am not sure if there are any left though. The final drives of the mr2 and alltrac share the same part number so this should work for us.

It equates to 5% more usable torque but a lower top speed.

You can use the calculator to see how it might affect your power band.
http://mr2oc.com/showthread.php?t=28712 ... inal+drive

This would be an alternative to using the rav 4 gearbox and keeping the stronger internals of the alltrac box.

I ran my number through the calculator and even running my over-sized tires my final drive would still be slightly lower than stock with stock tire size.
 

CMS-GT4

Active member
There is a gt4dc member from Russia who is opening up shop for fabricating parts. He can do custom final drives for our boxes in the $500 usd range. This is likely the path I will be going when it comes time for my gearbox project.
If there is interest we can get a group buy of 5 or so down the road.

He is also possibly offering a close ratio dog box for much less than the c-one unit.
 

CMS-GT4

Active member
Just for comparison I wanted to post the EVO 9 5 speed specs to compare to the gtfour boxes.

Curb Weight: 3,263 lbs (EV0) 3,219 lbs (EVO RS)

1st: 2.785:1
2nd: 1.950:1
3rd: 1.444:1
4th: 1.096:1
5th: 0.761:1
Final drive: 4.529:1

Tires: 235/45ZR-17
 

Flying Bajan

New member
Very interested in these "Russian" final drives / gear kits indeed ! However, as my car is a pure street car, I am not interested in a straight cut dog engagement kit, but rather a closer ratio helical cut syncromesh kit that will work with the stock bearings, syncro cones, etc.

That's one of my main attractions to the C-One kit - however repulsed I may be by the price ! :)

Basically, I am trying to achieve a top speed of 130 to 140 mph max at 7,500 RPM in 5th gear on 225/45/17 rubber, and reduce the gaps between 1st and 2nd gear especially, without raising 1st gear to a level that getting the car off the line in a "spirited manner" is difficult.
 

CMS-GT4

Active member
We have to have at least 5 definite buyers then he will make them. I am working on the funds right now for it.
 

Flying Bajan

New member
Will it be a FD, a gearkit or both ?

Will it be a syncromesh gearkit or dog box ?

What ratios for the gearkit and FD ?

Cheers !
 

CMS-GT4

Active member
He is offering a gearset too, when there is enough interest.

Prochorus familiaris":3ojiur5j said:
The 1st question:

Now we are on decision - to make or not to make?

The talk is about close ratio gears, for our cars (GT4) it's produced only by C-One in Japan, look it here:

http://www.c-one.co.jp/C-ONEPARTS/close_mission.html

Their price is 2800$ ExWorks, with airdelivery it will be up to 3500$ because of "nice" weight of the parcel.

We can do make the stuff like this, even upgraded, i.e. little bit more nicely selected ratios, more stronger steel, more tough treatment of the material, etc.
We have some tech claims to C-One stuff, because we have in our team (consists of 1 ST185 & 4 ST205 for rally + 3 ST205 for writing the verbatim before the rally) in competition with dog-gang gearboxes, and C-One sometimes give us the problems of damage & in some sense we aren't pleased with ratios selected, so there is a space for improvement & upgrade.

Our project price will be 1800$, i.e. minus 1K$ at least. May be even more cheaper, it's hard to say before production start.
Also our delivery will be much cheaper, because it based on lower tariffs.

Now we are on the decision point - to make or not to make?
We don't want to make it & then to put it on the shelf as in museum.

SO - Do you think it could be interesting for you?
Please input your IMHO. For us to estimate the demand.

Any questions are welcome.
 

Flying Bajan

New member
Consider me heavily interested with cash waiting. As long as it is not a dogbox and the ratios suit my purpose.

I'm THIS close to buying a C-One kit, but the price is turning me off. If there was another (as good or better) alternative at a reduced price, I will be all over it.
 

CMS-GT4

Active member
Not really. I have not heard of any parts delivered and tested yet. Once I hear more info, I will post and update.
 
CMS-GT4":6bogj0w0 said:
He is offering a gearset too, when there is enough interest.

Prochorus familiaris":6bogj0w0 said:
The 1st question:

Now we are on decision - to make or not to make?

The talk is about close ratio gears, for our cars (GT4) it's produced only by C-One in Japan, look it here:

http://www.c-one.co.jp/C-ONEPARTS/close_mission.html

Their price is 2800$ ExWorks, with airdelivery it will be up to 3500$ because of "nice" weight of the parcel.

We can do make the stuff like this, even upgraded, i.e. little bit more nicely selected ratios, more stronger steel, more tough treatment of the material, etc.
We have some tech claims to C-One stuff, because we have in our team (consists of 1 ST185 & 4 ST205 for rally + 3 ST205 for writing the verbatim before the rally) in competition with dog-gang gearboxes, and C-One sometimes give us the problems of damage & in some sense we aren't pleased with ratios selected, so there is a space for improvement & upgrade.

Our project price will be 1800$, i.e. minus 1K$ at least. May be even more cheaper, it's hard to say before production start.
Also our delivery will be much cheaper, because it based on lower tariffs.

Now we are on the decision point - to make or not to make?
We don't want to make it & then to put it on the shelf as in museum.

SO - Do you think it could be interesting for you?
Please input your IMHO. For us to estimate the demand.

Any questions are welcome.

Josh
Can you pm me his info, I'm looking for a dog set for my now destroyed 205 tranny I just took out, most likely it will be the RC ratio & final

Pat
 

ST185pinjo

New member
Pat, be carefull with this man.

He was on the GT4dc forum. Talking about making everything better than the big brands for about half the price.

I don't know if people there bought stuff off of him and send him money, but he is now where to be found.

Was looking for some info for you, but I see you are registered. :wink:
 
ST185pinjo":13y2lzc3 said:
Pat, be carefull with this man.

He was on the GT4dc forum. Talking about making everything better than the big brands for about half the price.

I don't know if people there bought stuff off of him and send him money, but he is now where to be found.

Was looking for some info for you, but I see you are registered. :wink:

Thanks for the heads up. I'll try to visit you guys over there more often

Pat
 

DudeMan

New member
CMS-GT4":1whxhyo8 said:
Alltracs might get much more out of their ct26, ct20 or ct27 with a lower final drive.

I'm confused.. Wouldn't a lower final drive hurt performance?

Isn't this why people are dropping the 4.285 FD into RC transmissions?

Not saying your wrong or anything.. Just some conflicting info here..
 
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